package org.spring.config.server.page.table;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.springframework.core.MethodParameter;
import org.springframework.util.CollectionUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

import com.google.common.collect.Maps;

/**
 * 
 * ClassName: PageTableArgumentResolver <br/>
 * Function: TODO ADD FUNCTION. <br/>
 * Reason: TODO ADD REASON(可选). <br/>
 * date: 2019年10月14日 下午6:03:43 <br/>
 *
 * @author dengqian
 * @version
 * @since JDK 1.8
 */
public class PageTableArgumentResolver implements HandlerMethodArgumentResolver {

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        Class<?> cla = parameter.getParameterType();

        return cla.isAssignableFrom(PageTableRequest.class);
    }

    @Override
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
        NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
        HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class);

        PageTableRequest tableRequest = new PageTableRequest();
        Map<String, String[]> param = request.getParameterMap();
        if (param.containsKey("start")) {
            tableRequest.setOffset(Integer.parseInt(request.getParameter("start")));
        }

        if (param.containsKey("length")) {
            tableRequest.setLimit(Integer.parseInt(request.getParameter("length")));
        }

        Map<String, Object> map = Maps.newHashMap();
        tableRequest.setParams(map);

        param.forEach((k, v) -> {
            if (v.length == 1) {
                map.put(k, v[0]);
            } else {
                map.put(k, Arrays.asList(v));
            }
        });

        setOrderBy(tableRequest, map);
        removeParam(tableRequest);

        return tableRequest;
    }

    /**
     * 去除datatables分页带的一些复杂参数
     * 
     * @param tableRequest
     */
    private void removeParam(PageTableRequest tableRequest) {
        Map<String, Object> map = tableRequest.getParams();

        if (!CollectionUtils.isEmpty(map)) {
            Map<String, Object> param = new HashMap<>();
            map.forEach((k, v) -> {
                if (k.indexOf("[") < 0 && k.indexOf("]") < 0 && !"_".equals(k)) {
                    param.put(k, v);
                }
            });

            tableRequest.setParams(param);
        }
    }

    /**
     * 从datatables分页请求数据中解析排序
     * 
     * @param tableRequest
     * @param map
     */
    private void setOrderBy(PageTableRequest tableRequest, Map<String, Object> map) {
        StringBuilder orderBy = new StringBuilder();
        int size = map.size();
        for (int i = 0; i < size; i++) {
            String index = (String)map.get("order[" + i + "][column]");
            if (StringUtils.isEmpty(index)) {
                break;
            }
            String column = (String)map.get("columns[" + index + "][data]");
            // if (StringUtils.isBlank(column)) {
            // continue;
            // }
            String sort = (String)map.get("order[" + i + "][dir]");

            orderBy.append(column).append(" ").append(sort).append(", ");
        }

        // if (orderBy.length() > 0) {
        // tableRequest.getParams().put("orderBy",
        // " order by " + StringUtils.substringBeforeLast(orderBy.toString(), ","));
        // }
    }

}
